Memory for use in electronic telephone system



P. E. osBoRN 3,046,348 MEMORY RoR USE 1M ELECTRONIC TELEPHONE SYSTEM July 24, 1962 8 Sheelas-SheeiI 1 Filed Oct. l2, 1959 Affy.

MEMORY FOR USE 1N ELECTRONIC TELEPHONE SYSTEM Filed Oct. 12, 1959 P. E. OSBORN July 24, 1962 8 Sheets-Sheet 2 Fm. ZA

P. E. OSBORN MEMORY FOR USE IN ELECTRONIC TELEPHONE SYSTEM Filed Oct. l2, 1959 8 Sheets-Sheet 3 8/ f CP L57 il? 6%- rovF/asaj N 265 c' 9 ll 5l 7 Al PP g; 5 0

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MEMORY FOR USE IN ELECTRONIC TELEPHONE! SYSTEM Filed OCT.. l2, 1959 8 Sheets-Sheet 4 FROM F I6. 2B

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N i l?) MEMORY FOR USE 1N ELECTRONIC TELEPHONE SYSTEM Filed Oct. 12, 1959 P. E. OSBORN July 24, 1962 8 Sheets-Sheet 5 Nm. .mi QR S QQQQ QQGQ m v N t mfu Ql nimm Mmmm .umm

MEMORY FOR USE IN ELECTRONIC TELEPHONE SYSTEM Filed Oct. l2, 1959 July 24, 1962 P, E. osBoRN 8 Sheets-Sheet 6 Q. www Nm Q m L C D P S w m M 0 m Q N PG f A w P. E. osBoRN 3,046,348

E 1N ELECTRONIC TELEPHONE SYSTEM July 24, 1962 MEMORY FOR US Filed OCT.. l2, 1959 8 Sheets-Sheet 7 MS RS E E:

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MEMORY FOR USE 1N ELECTRONIC TELEPHONE SYSTEM Filed oct. 12, 1959 P. E. OSBORN July 24, 1962 8 Sheets-Sheet 8 K C 0 a 7. J G HW H G m 2,0 3.0 TIME IN MICROSECONDS 67 DIP HG. 8 LOW SPEED CLOCK 8 l2 /6 20 24 28 3234 T/ME /N MICROSECONDS P/ GP5 SYSTEM PHASEH 900 IDL-y FIG. 9

ilnited States @arent 3,046,348 Patented July 24, 1962 ffice 3,046,348 MEMORY FOR USE IN ELECTRONIC vTIELEPI-IONE SYSTEM Peter E. Osborn, Addison, Ill., assigner to Automatic l'Electric Laboratories, Inc., a corporation of Delaware Filed lOct. 12, 1959 Ser. No. `845,736 15-.Claims. (Cl. 179-15) This ,invention relates in lgeneral to a communication system 4and more Yparticularly to a 'ferrite core distributor and ymemory system for .a small electronic telephone switching system. More particularly, this invention covers a memory for a telephone system employing a time division multiplex technique for `intra-oilice transmission similar to that disclosed in copending yU.S. application of A. H. Faulkner and D. K. Melvin, Serial No. 843,380 tiled on September 30, 1959. The subject matter of this invention therefore relates tothe .particular circuitry and techniques employed inthe memory and associated circuitryof such a telephone system.

An object of this invention shall be to provide a highspeed ferrite core -memory with associated circuitry, for use in 1a -small Aelectronic :telephone time-division multipleX'swi-tching system. One feature of this invention is a memory `facility for the storage of information regarding a telephone call lbetween appearances in a time interval associated with the call. A second feature shall be the providing of lthis information -upon demand of logic circuitry tolinitiate-commands to'line circuitry in a transmission network. Another feature vof this invention is the application of a current steering principle 'to the pulse di-stributors that are associated with the memory. A still further object of this invention shall be to provide a memory system for the control of transmission between calling and called parties, and also the control of necessary switching functions associated with the establishment and ultimate disconnection of a call.

In the control of a telephone switching system like that disclosed in the `aforementioned ,copending application difticult problems arise such as the proper sampling of the audio signal in :the transmission network, the proper use of logic-circuitry and the storage and use of information required to -aect and `maintain the interconnect of the two telephone subscribers. This invention proposes a high-speed ferritecore memory and associated circuitry for use in such small electronic telephone switching systems. The memory itself is an application of the high-speed ferrite core Ymemory and the pulse distributorsincludeapplication of the current steering principle.

A primary function `of the .memory is to store information regarding a call between appearances ofthe time slot associated with `the call, and to provide this information upon demand of logic Acircuitry `to initiate commands to the proper line gates in .a transmission net-work. The information stored will be the telephone numbers associated with the calls and the supervisory informatiomsuch as thesendingof ringing tone, busy tones, dial tone, ring back tone, and switching the call through.

The specific requirement `.of `the .system is to provide forty time slots fof two microseconds duration; :this time slot is divided into two parts, the first 1/2 microsecond used to read out `.the .memory and ito clampthe common highway 4ground and the last 11/2 microseconds to provide write-in .time for the memory .and to provide 'the transmission :time'for the'tirne slot. The pulse that occurs in the virst M2 microsecond is referred to as a read pulse, the pulse occurring for 1-1/2 microseconds will ibe referred to .as Ya write or half-write pulse.

FIG. 1 is a `system block diagram.

FIGS. .2A and .2B are functional .diagrams of the lowspeed clock.

2 FIG. 3 is a functional diagram of the low-.speed .distributor.

FIG. 4.is.a functional diagramtof the low-speed memory. FIG. 5 is a functional .diagram of the high-.speed distributor.

FIG. y6 is a functional diagram of the high-.speed memory.

FIG. 7 is agraphof the high-speed clock pulses.

FIG. A8 yisa graph .of thelow-speed clock pulses.

FIG. 9 'is a functional. diagramof the system phaser.

Referring to FIG. l, the exchange which is similar 'to that vdisclosed in .the copending application of A. Faulkner and D. K. Melvin, Serial No. 843,380, tiled September 30, 1959, includes k line circuits .'LC11 .to LCtltl associated .with stations S11 to S00, and a plurality of link circuits LK1 to LK20 interconnected by a time ydivision .multiplex-transmission 4highway MLl--MLZ having a transmission control unit interposed therein.

Any two line circuits vmay be .electively connected through `any `link circuit by selectively supplying control pulses to them.

The signaling circuits 170 supply supervisory .tones which are .transmitted by time division multiplex over line 172 and the .highway `MLl---MLSZ to the line circuits of calling lines. The signaling circuits 170 also supply ringing control signals over conductors in the control line 13410' the vline circuits of called lines.

The function of remembering which circuits are interconnected on a time idivision multiplex basis over highway M'Ll-MLZ yand of supplying control pulses -to the selected ltransmission gates in the appropriate time slots is performed by a high-speed memory 600 lin conjunction with a line number register and a signal state register 190. The control lpulses' are supplied Ato the line circuits over line 134, rto the link circuits over -lines YDP and S-T, and .to the signaling-circuits over line 162.

Ehe selective registration 1in the high-speed memory through the line number register 130 and the signal state register .190 is controlled fby ythe .register control circuits 150. These circuits control the line finding function of scanning .to iind a line which has initiated a call and causing-a connection to be established to the calling line; and the connector function of `detecting .dial pulses from the l'callingline and causing aconnection to :be established :to the called line. These `control circuits are shared 'by all of the 4links on la time division basis, using a .lowspeed memory 400 for storage.

High-speed clock 700, :low-speed clock 200 land .timing ,pulse generator 800 supply ,all -of `thefpulses required by the exchange.

Each of the memories 400 vand600 as shown in FIGS.

V4 4and .6, comprises a coordinate array of ferrite cores.

Infeach, `the horizontal rows Iare `associated with the links, and the ven-.tical columns are associated with JHip-flop type storage .devices in the associated units 150, 130, .and 190. .Each memoryiis .associated with a separate pulse distributor 300 .and 'Stlito .supply :pulses -to its horizontal conductors in turn. .Each :horizontal row has a read winding anda half-write Iwinding :threaded through `all of the cores of the row, and each vertical column has .asense'windng and a .half-write winding. For each of `the memories, during each stage of its distributor, "a read pulse is supplied through .the read winding of the row, causing vthe state of each core of the .row to be transferred -by means of the sense windings to the Hip-flops in the various registers. The-information in the -dlip-ops'is then `utilized and possibly altered by the associated circuitry. A vhalf- -wr'ite Apulse is applied -to fthe 'horizontal Winding, Iand coincidently :to selected :ones of the vent-ical windings to return the information from :the v@dip-flops ato the cores. This isrepeatedin turn, -for Leach .horizontal rowdu-ring successive stages of the distributor. The high-speed memoiy comprises cores in tive columns TC to TG for registering the tens digit, tive columns UC to UG for registering `the units digit, and ve columns BT, DT, RG, RT, and ST for registering the signal states. Each horizontal row is associated with one time slot of the multiplex transmission. Each stage of the distributor comprises a 0.5 microsecond read pulse followed by a 1.5 microsecond half-write pulse in a two microsecond time slot. The horizontal half-write windings are connected at one end to the distributor and at the other end over line DP to the link circuits for transmission control. The half-write windings of the iirst two rows are connected over leads DPI and DPZ to link 1 to control the calling party and called party transmission respectively. Successive pairs of horizontal rows are in like manner coupled to successive links, so that each link is permanently associated with two high-speed memory rows corresponding to two transmission time Slots, one for the calling party and the other for the called party. Also, during each of the 1.5 microsecond pulse intervals, `the line number register 130 translates the two-out-of-ve code registration of the tens digit to a one-out-of-ten code signal supplied to a conductor in line 134, and the two-out-of-ve code of the units digit is translated to a one-out-of-ten code signal supplied tor another conductor of line 134, to control the transmission in :the line circuit corresponding to this number. At the same time, the signal state register 190 controls the transmission of supervisory tones to the calling line, ringing to the called line, and switch-through of the link transmission gates, `as required.

In the register control circuits 150, the line supervisory circuit 150F receives hookswitch and line-busy information from the line circuits and registers this information in ilip-ops for use by the other circuits. The allotter circuit 150B assigns a scanning link to -a line which initiates a call. The `allotter is yassociated with the cores in column S of the low-speed memory 400 to register whether or not a link is scanning. The timer circuit 150C times the dialing and other hookswitch signals to determine when the sequence state should be changed. The timer uses the cores in columns FC, FD, FE, and FF to register the time interval on a binary basis, separately for each link. The sequence circuit 150D lregisters the sequence states of the links, which are: normal, tens dialing, units dialing, busy tes-t, ringing, and conversation. The sequence circuit uses the cores in columns HC, HD, and HE to register these states on a binary basis for each link. The dialing supervisory `circuit 150B is provided to insure that the control circuits do not respond more than once to each dial pulse. This circuit uses the cores in columns B and R, column B being set for the duration of a digit, and R `being set only for `the duration of a dial pulse. The line-number-advance circuit 15015 supplies advance or rewrite signals to the line number register 130 to control the number registration in the high-speed memory 60). The output pulses from high-speed clock 700 drive distributor 500 for driving the high-speed memory 600 and supplies pulses for the transmission circuit. The output of the high-speed clock 700 also drives a low-speed clock 200 which includes a seventeen stage distributor primarily for controlling logic circuits in the register control circuit 150. Pulses from the low-speed clock 260 also drive a distributor 300 which drives the low-speed memory 400. A timing pulse generator 300 is driven `by pulses from distributor 300 to control the timer circuit 150C.

In reference to the pulses, the following definitions relate to the terms used in this application:

Time slot--a two microsecond interval, being one complete cycle of the high-speed clock 610. Each time slot comprises a 0.5 microsecond guard interval followed by a 1.5 microsecond interval during which transmission and various control operations take place.

Transmission cycle-a time interval comprising 40 time slots or 80 microseconds, being one cycle of the distributor 500.

Logic cycle-a time interval comprising 17 time slots or 34 microseconds, being one cycle of the low-speed clock 200.

Frame-a time interval comprising 40 logic cycles totaling 680 time slots or 1360 microseconds, being one cycle of the distributor 300.

Timer step-an interval of 20.4 milliseconds, being one cycle of the timing pulse generator 800.

Coincident-used with reference to two or more signals which overlap in time, usually at the input of a gate.

Simultaneous-used with reference to signals or events occurring during the same time cycle, such as a transmission cycle or a frame, although possibly in different time divisions of the cycle.

FIG. 7 is a graph of the pulses produced during each time slot by the high-speed clock 700. The pulses on lead CPO.5 occur during the guard interval and have a duration of 0.5 microsecond. The pulses on lead CP1.5 occur during the remainder of the time slot and have a duration of 1.5 microseconds. The pulses on lead CPlA and CP1B each have a duration of one microsecond and occur during each time slot as shown.

The distributor 500 has forty stages and is driven one stage per time slot. The input is supplied by the pulses on leads CPiLS and CPLS from the high-speed clock 700. Each stage drives a row of the high-speed memory 600, and has two output leads threaded through the cores of the corresponding row. One of the outputs of each stage is a 0.5 microsecond pulse for applying a readout potential to the cores. The other output from each stage is a 1.5 microsecond signal for supplying a halfwrite potential to the cores. The leads from these outputs extend through the memory 600 to the distributor pulse leads DP1 to DP40, which are connected individually to transmission gates of the links. Lead DP1 is connected to the calling side transmission gate, and lead D132 is connected to the called side transmission gate of link 1. The succeeding pairs of the leads DP are connected to succeeding links, each odd-numbered distributor pulse being supplied to a calling side gate, and each even-numbered distributor pulse being supplied to a called side gate of `a link. Thus each of the forty distributor pulses corresponds to one time channel of the multiplex transmission, and is permanently associated with a link transmission gate.

FIG. 8 is a graph of the pulses produced by the lowspeed clock 200. This clock is driven by pulses on lead CPIB and CPLS from the high-speed clock 700, and is driven one stage per time slot. There are seventeen stages in its cycle for a total of 34 microseconds. The output of the first three stages are combined to produce a continuous six microsecond pulse on lead P1. During each of the stages 4 to 13 output pulses are produced on leads P2 to P11 respectively each having a duration of 1.5 microseconds coinciding with the pulse on lead CPLS. The output of the stages 14 to 16 are combined to produce a continuous six microsecond pulse on lead P12. During stage 17 -a 1.5 microsecond pulse is produced on lead P13. The pulses P1 to P13 comprise one logic cycle.

The distributor 300 has 4forty stages, and is driven one stage per logic cycle by input pulses on leads P1 and lead P12 from the low-speed clock 200. The output from the even-numbered stages are used to drive the horizontal rows of the low-speed memory 400. There are two leads for each row. On one of the leads a readout potential is applied during the interval coinciding with the pulse on lead P1, and on the other a half-write potential is supplied during the interval coinciding with the pulse P12. Each of the horizontal rows of the memory 406 is associated with one of the twenty links. Thus during each logic cycle a read-out pulse is supplied vto one of the rows during thepulse interval P1, transferring lthe information in this row into the vcircuits of the register control vcircuit 150. During the pulse in- `tervals P2 to Peli various logical operations occur in the circuits 150A-to 1`50F, which vmay alter some 'of this information. During the :pulse interval P12 a half-write potential is applied to this horizontal row and to the selected-ones'of the Vertical columns to write the information back into the cores. During the pulse interval P13 the'flip-ilops vintheregister control circuits are cleared in preparation for the next logic cycle, which corresponds to another link. -f

'1n 'this -system lthere are two groups of time division multiplex circuits having different distribution cycles,'one ofthe groups -beingassociated with the high-speed mem- `ory 6fm, iand the other group being associated with the low-speed-memory 400.

The high-speed circuits control the time division transmission of 'vo'ice and 'tone `signals over the multiplex line MB1-ML2. Referring to FIG. '1, and also to FIGS 5 land '6, 4the high-speed 'circuits include the highspeed clock J70th-the 'high-speedmagnetic distributor Stit', `the'high-speedjmemory 600, as ywell as the line number register 130, the signal state register 19t?, all ofthe line circuits LC11 to LCM, all vof the link circuits LKl to LKML .the signaling circuits 179i, and the transmission control unit "110. The high-speed Lclock 760 has a cycle of two micro-seconds which is referred to as a time slot. As shown in FIG. 7, the time slot is ,divided into 0.5 microsecond intervals, corresponding to the respective outputs CPO.S and CP1.5 `from the clock. The output .pulses from .the clock '700 drive the high-speedmagnetic distributor 500. This distributor has forty stages of two microseconds each, making a total cycle .of eighty microseconds. Each cycle .of this distributor is one .transmission .cycle on the multiplex line MLl--ML2', and each stage occurring in successive cycles comprises `one transmission channel. In each channel transmission occurs during lthe 1.5 microsecond interval, andthe 0.5 microsecondiinterval is used as a guard interval between .channels The distributor 50i) has two .output leads for ,each stage, and for .each stage the pair of output `leads are .threaded through one horizontal row of the .high-speed .memory 660. On ,one of .the leads a read .pulse .is delivered `during the 0.5 .microsecond interval, .and .on .the other .a half-write .pulse is delivered during the 1.5 microsecond interval. The writing leads extend through the ,memory and thence to vthe links to form .the Eprincipaldistributor pulse output leads. These forty .DP .leads are grouped .in successive pairs extending to `the twenty links. For each link the odd-numbered ,DP 'pulse is used for controlling Y'the calling line gate,l and the even-numbered pulse is used for controlling the called line gate. Thus, each link uses two adjacent ,channels in the transmission cycle for a connection Ybetween two lines.

The line number register 130 in conjunction with the `associated cores in the high-speed memory 6th) delivers pulses to the line circuits in coincidence with the pulses delivered to the link transmission gates with which they khave been'selectively connected.

r4In accordance 'with stored information in the 'high- -speed memory 600, vthe line number register 13@ delivers pulses -to vthe line Icircuits, and the signal state register delivers pulses 'to -the signaling circuit 170 and tothe 4linkcircuits LK1 to 'L'K20,'so that'for each vchannel for which'a connection 'has been established, two ytransmission gatesconnected to the multiplex line, one at the end ML1 rand'the other at the end ML2, are pulsed in coincidence.

The low-speed circuits provide for time division sharing -of -the circuits used Ainperforming, most of the logical .operations ,required by the links to set up connections between lines. Referring to FIGS. 1, 2A, 2B, 3, and 4,

these circuits comprise the low-speed clock 260, the lowspeed magnetic distributor 360, the Llow-speed memory 400, the register control circuits d50, and a timing pulse generator l800.

The low-speed clock 26d-Tis a distributor which produces thirteen output pulses requiring a Ytotalof seventeen time slots or 34 microseconds, as shown in FIG. 18. This clock cycle is referred to as a logic .cycle and is `one time division of the total lowspeed cycle. The lowspeed magnetic distributor 300,driven by the vpulses `P1 and P12 from 'the -output -of the low-speed clock, has forty stages. Each `cycle of this distributor is oneconiplete lowspeed cycle, and is referred to as a frame. Thus, such frame comprises forty logic 'cycles orga total of 1360 microseconds. The even-numbered Astages of the distributor '3% are-used to drive theetwenty rows of the `low-speed memory 400, each delivering a read pulse during `the pulse interval P1 and a half-write pulse vduring the pulse interval P12. Each of these memory rows, driven by an even-numbered stage of the distributor 3061, corresponds to Yone of the links.

v During each such logic cycle which corresponds to a link, inthe pulse interval Pil information is transferred from the low-speed memory '400 'to the register control circuit 15h; during `the pulse intervals P2 :to tP-lit the line supervision leads C and E are analyzed, the-information obtained `'from the 'line circuits and memory lis used to perform logical operations and to deliver 'appropriate output signals to the line number register as well as to the signal state register 190; during P12 lthe information, which may or may not ,have been altered, is transferred back into 'the -same "row `of the memory 490; and during the pulse interval P13, the register control circuits 150` are cleared in preparation .for the logic cycle of the next link. Thus, during each frame, each link sharesthe register control circuits 15) `for one logic cycle, .with alternate logic cycles 'being unused.

Thus,the logic vcircuits are time shared at a low repetition rate to permit time to perform the various logical operations, while Athe ktransmission circuits are time shared at the high repetition rate required for the faithful reproduction of voice signals. Y'

The pulse .repetition rates of the different distributors Vare so arranged that vthe logic state of each link is analyzed and acted on once and only once per frame. The Aidentity of which link is associated with a logic cycle yis established by coincidence ycfa .given'logic pulse with a pulse `of thehigh-speed circuits. To accomplish this the period require only ,one itirne position of the transmission cycle.

The trunk circuitcould then befidentiiied in the low-speed ycircuit by the coincidence of the pulse'PZof a logic cycle with the single transmission cycle pulse.

Before examining the detailed circuitry of applicants invention an understanding of -the timing .relationship .between the high and low-speed vmemories shouldbe undertaken.

vClock ,pulses :CPLS and CPLS from the 'high-,speed yclock 800 .are used as linput pulses for the read and write pulses in the high-speed magnetic pulse distributor '500 and associated memory 600. The high-speed distributor 5M) Vcounts these pulses and distributes them in 'fortyseyquential V.stages to `the `forty vertical rows lin the 'highspeed memory. As each row 'is read out the information is stored in the associated register circuits '130 and '190 where it provides the line gate pulse as operated on by the logic so that the same or dilerent number can be written back into the memory.

The CPLS pulse continues through the memory where it provides a half-write and onto the link circuits where it provides the link gate pulse. Thus while the tens and units registers are writing in the memory and pulsing a line gate the DP pulse is pulsing a link gate and the line and link are connected in that time slot.

CPO.5 is also going to the low-speed clock 200 where a count of seventeen is obtained; three counts going for P1 and three counts going to P12 with the other eleven counts providing P2 to P11 and P13. The relation between the low-speed clock 200 and the high-speed distributor 5G() is such that every seventeen times the highspeed distributor circulates it will re-enter the same relationship with the low-speed clock. That is to say that DPI will coincide with P2 every seventeenth time that DPI appears since the low-speed clock count is a prime number then in seventeen circulations the high-speed distributor P2 will have coincided with every DP pulse one time and the low-speed clock will have recycled forty times.

The P1 and P12 outputs of the low-speed clock 20@ are used as the read and write pulses for low-speed distributor 360 and low-speed memory 400. The lowspeed distributor has forty stages and therefore cycles one time for every forty cycles of the low-speed clock 200 or seventeen cycles of the high-speed distributor 590.

The low-speed memory is read out of during P1 into the low-speed register 150. Logic functions are performed during P2 to P11 pulses, and the memory is written back into during P12 pulse. The low-speed registers are reset during the P13 pulse.

The time slots operated on are those coincident with the P2 and P3; P2 for the calling time slot and P3 for the called. ln the memory the odd-numbered rows are for the calling party time slot and the even-numbered rows for the called party time slot. There is one lowspeed memory row for each link with a maximum of twenty links or twenty low-speed memory rows. Since even-numbered time slots are never calling party time slots, then the coincidence of a P2 pulse on any evennumbered time slots are never used and these rows do not appear in the low-speed memory. The low-speed dis- .f

tributor 360 outputs corresponding to these rows are simply grounded.

The fortieth output from the low-speed distributor 300 is used to provide the trigger pulse for the timing pulse generator 700 which is a count of fifteen thus every 'fifteenth time the low-speed distributor cycles a P29 pulse will be provided in the timing pulse generator.

Shown in detail in FIG. 5 is the high-speed ferrite core distributor used to supply the appropriate pulses to the high-speed memory 606. The purpose of the distributor is to receive pulses from the high-speed clock 700, change them into CPO.5 and CPLS pulses by suitable driver circuitry and distribute them as read and halfwrite pulses respectively to the forty rows in the memory one row at a time. In an electronic PABX telephone system such as disclosed in this application there are forty time divisions of two microseconds duration each. It is the purpose of the distributor to separate the 80 microsecond period into forty distinct time divisions. Thus it is the job of the distributor to assign a particular time slot to each of the forty rows in the memory and the distributor must `be of a design so any particular row always receives the same time slot.

CPLS pulse from the high-speed clock is used to drive hip-flop 511 to its alternate states. The outputs of this ip-flop are combined to a series of AND gates 512, 514, 521 and 523 with the output of an amplifier 518. This amplifier in turn was driven by delay line 517 which was supplied either a CPlA or CPGS from the high-speed clock 700 through gate circuit 516. The outputs of the aforementioned gate circuits 512, 514, S21 and 523 are amplified by ampliiiers 513, 515, 522 and 524 respectively. The first two outputs being used to drive twenty stage distributor number 530 and the second two for twenty stage distributor number 540. These pulse distributors receive the input pulses from a high-speed core driver circuitry as previously mentioned over four input leads. One pair of leads has the even-number read and Write pulses and the other pair has the odd-number read and write pulses. Each pair of pulses will drive its respective twenty stage distributor circuit.

Referring now to distributor 540 on FIG. 5 and assuming an initial condition of ferrite core 541 is state l and all other cores in state 0, the first incoming read pulse supplied from amplier 522 must pass through the primary winding of all cores in the read row S41, 542, 543, etc. Since core 541 is the only core in state 1 and since read pulses are positive, then core 541 will be set to state 0 and all other cores in the read row will be unaffected. By setting core 542-1 to 0 a voltage will be induced in a secondary in such a manner as to cause most of the input current to pass through the secondary of core 541. The current passing through the secondary is such that it tends to prevent core S41 from setting to O; thus the difference between the current in the primary and secondary windings will be the ampere turns available to switch the core. The proper design of the primaries and secondaries of core 541 will cause core 541 to take the entire duration of the read pulse to switch. The core must switch all the way to state O but must not complete the switch before the read pulse ends.

Since all the other cores in the read row were already in state O they will be only slightly affected by the read current and only a very small amount of voltage will be induced in the secondary of these cores. lt is this voltage drop on the primary that limits the number of stages in the distributor. Since each core represents a small LC circuit there is a slight time delay at each core. lf the overall time delay is too great the circuit will not operate because the secondary of the one switching core will seem a very large impedance during the time delay, and no current will flow in the secondary during the delay. The ampere turns switching the core is equivalent to the primary turns minus the secondary turns. During the time current in the secondary is equal to 0 the core will be switching so fast that it is possible to switch the core to the 0 state before current in the secondary can start to ilow.

Most of the input current is steered through the secondary winding of core 541 down through the tertiary winding of core 561 and through the read winding of the first row in the high-speed memory 600, setting the memory cores to state 1.

At the end of the read pulse, a write pulse from amplier 524 enters the write row, cores 561, 562, etc. This pulse sets core 561 to state 0 and steers the current through the secondary winding C of core 561 to the tertiary winding of core 542 setting it to state l and through the half-write winding of memory row number 1 in memory 609.

During the next two microseconds, a read and write pulse will enter the even-nuinber pulse distributor 530 and they in turn will be sent to memory row number 2. The next read pulse to enter register 540 will set core 542 to 0, steer the current through to tertiary winding C of core 562 and to memory row 3. The following write pulses will set core 562 to 0, steer the current to the tertiary winding of core 543 and to the half-write winding of memory row 3. This distributor will continue to send each pair of rewrite inputs to succeeding memory rows. the twentieth write pulse will switch core 580 to state 0, switch core S41 to state 1 and enter the half-write winding of memory row number 39. Thus at the end of the twentieth write pulse the distributor is back to its initial anew cycle.

The high-speed memory-600 shown in detail FIG. 6 consists of forty-one horizontal rows Iandiifteen vertical columns. vThe 'first twenty-eight rows are :for link circuitsywith rows'twentyenine to-fortybeingused for trunk circuits and irow forty-one--for'the ltransfer circuit. The first Y'tive columns are `for the registration of the tens digit, the next -five columns Uare Vforthe registration of `the units digit and the last viive columns are for the registration rof supervisory circuit Ainformation viz: dial `tone (DT), busy'tone (BT)r,ring'generator (-RG),ring Abacktone (RT) and switchthrough (ST).

IEach horizontal row has two windings, a 4read and ya half-write winding, thatare fed by the pulse'distributors '550 or v'540. The even 'rows Ibeing fed from distributor '550 Vand-the odd from-distributorSZI-O. Read out is accomplished lby reading out an entire row at a time giving an Vadvantage that ythe tread yampere turns canflbe very high Aassuring afast `read out,(% of a micnosecond) and preventing any chance ofoperating a core on a minor hysteresisV loop. Since 4the read `and write windings are `called for. At the same time thesengenerators -are'providing vhalf-write f in `certain vertical columns, .the rowthat Separate windings, the actual current for the read and half-.Write windings can be the --sameg `this provides a constant currentndrain on the core'driver'powersupply as opposed :to fluctuating current Ydrain if the currents were-notofequal amplitude.

-Due to :the previously rdescribeddistributor operation each row will receive a 1/2 lmicrosecond read .pulse followedfby :111/2 microsecondihalf-write pulse. "llhesepulses can not appear in any other ro-w at'thistirne (with the exception of row.41^whichwill be explored later), and will reappear in this row .every 80 microseconds. The read winding-is such 4that a read pulse will assure that all cores ina -row willrbe set to .'state.0. The half-write winding will provide half the ampere turns necessary Vto Aset :the .core :to vstate 1, but will notaect the State of thecore 2by itself. The halfewn'te winding terminatesin a :pulse vvtransformerin a link or'trunk'circuit, thepurpose of :which -is 'to provide the link or trunk gate v.time slot pulse.

Each columnhas two windings, a-sense winding and a half-write winding. .One end ofthe sense winding-is Iconnected :to a voltage dividerfthat :provides ,a negative .half volt termination, the other termination is the S1 .terminal on a .register .flip-flop in .either register 1&0 .0r 190. :The negative termination prevents rte-setting .of the flip-nop tona noise signal. One register vnip-flop is associatediwith each column, to gset-a core 1in any one row from to 1;;positive voltage will vlue applied to the set 1 Uf fthe associated fip-fiop, setting -it to state 1. These -iiipiiiovps arezreset to StateOJby clock pulse CPtrS which :in turn coincideswith the Aread ipulses in the horizontal rowsr. mean'sthat when a core is readout (set from state @l fto-,state 0) Aproviding a voltage on set 1a voltage also appears on I,set 0. The .design is such that set 1 willfoverride set 0 andthe ipfflop-,will fbers'etto-state 1. Two `microseconds .later CPO:5 will 1 again appear '.at `the gregister ilip-op and reset it -to .state 0 unless the next l.row yalso has information in Vthat particular column.

Each vertical half-write 4winding 'has a constant current `.generator :associated with it. Operations of these gen'- ;erat or.s .are controlled 4by .logic circuitry :receiving information from register Hip-flops. On the rewrite-*condition the same columns receive a half-write-pulse; on the -adv ancecondition other columns-willbewritten into. These .generators .are `.gated .from the pulse coincidence CP1.5

. tandthereforecan only be turned on. during the same time .as the horizontal half-.write pulse. Under these condiditions .if :a .row is .read ,out :all Aflip-hops `associated in .thatrow .thatwere yin .state `.1 .will be set to state 1, at the end of -a 1/2 microsecond pulse allottedsto the read ,pu1seconstant.current ygenerators 4will Vlbe turned on fand ,provide a `.half-write pulse either'in the-same column as was -read out will'be gettinga half-write in the horizontal row. All cor-es receiving both .horizontal .and vertical half-write =will be set 1 all other cores will be unaffected.l The vrow then storesinformation as to .which flp-ops-are .tooperate inrthis time slot when thenextghorizontalread out appears S0 microseconds later. ABy using a two .out of iive code it is .possible to get ten combinations outof iive cores or one-hundred comlbinationsout vof ten cores.

In each link (the rst twenty-eight rows) of memory 600, are tworrofws; the odd-number now is for .registration of the calling .party number and thenext-even-numbered rowis for registrationof `the called party number. Each link gate is permanently connected to a'DP leadztO receive the half-write pulse .of a row. This means .that each link gate has a .definite time slot associated `with it. The `one link gate that is pulsed by a DPis directly connected I'back to a link gate set lby a DP. This indicates that thecalling and called party time slots `arealways adjacentreducing the .possibility .ofcross talks'ince only one side ,of eachtimefslot is adjacent to an uninterested time slot. Although trunk .circuitry is not required of the telephone system disclosed in this applicationconditions for trunk circuits .are made in rows 29 to 40. Since each trunk circuit need register only one party number; the trunk .circuit needsonly one row and one timeslot is therefore permanently gated from the TDP minus impulse of a trunk row.

In addition to the fourteen links (28 rows) and .the

twelve trunks (12 rows) there `isa forty-irst row called the transfer mow. Transferring from vany :given row to .any otherrow `can ybe `accomplished .-by lthe transfer row.

This may be understood by assuming that it is .desired to transfer the number registered in row .1 to row 40.

uAfter-row 1 `has 'been readout of the register will V,place ffhalf-writelpulses back to the columns that were read out .of. A-t the same time thisfrow 1 receives a half-write pulse a similar pulse willlbe sent ;to the .transfer row and both row 1 and row 41 will write in the same relative cores. The cores in row 41 will remain in this stateuntil the read pulse vappears in row40. At the lsame time that row 40 is read out of the transfer row will be read out.

y ynation at thefendof the verticalcolurnns. .Sinceit is desirable to have 4a -5 lvolt bias ,during the -write .time `and .a -5/10 volt `lbias during the readvpulse. Having the bias of .-5 Vvolts dur-ing the writepulse means the half-write ,noise spike dueto Ithe half-writenoises ypicked upffrom .thirty-nine cores .in 'the column that are not being `written `into rnnstexceed iive volts lbefore `it can affect the -registers. This rneans that the -high voltage spike `vwill not .causefalse operation .for 'the register .flip-flops. Flfhe V.Yari- .able .bias lis .provided by Iamplifier 60d -which .operates dur-ing CPGE: clock pulses .extending thenecessary i/10 `voltsfbias tothe sense :windingand when the ,CPtLS ,pulse is not present fthe amplier .is .turned `oif ,and .by appropriate circuit-ry allows the ybias voltage .on Vthe `sense winding yto rise to -5 volts.

Referring now to FIGS. '2A and 2B the low-speed clock is -shown in detail. The driver portion consists of a scale of two counter, 211, two write driver amplifiers ,216 and 218, a-read driver-amplifier 219 4and iaip-opZ. Pulse CPIB originating in the high-speed clock 700 is a one .mierosecond :pulse that starts vone microsecond after CP-155 also derived `from high-speed clock. 'When CPIB arrives .atrthe Elow-speed clock -it isn-.inverted by an rin-Venter .the read pulseor indiferentcolumns `if an vadvance is 75 213 .andisent on to -scale ofwtwo counter 2111frQm-'there l 1 extending to the inputs of AND gates 215 and 217, and from there to the two write driver amplifiers 216 and 218. The scale of two counter will change state with every pulse and therefore Ithis pulse will appear alternately on the two write amplifiers.

Flip-flop 212 provides `an inhibit gate to the CP1?) pulse. As long as this fiip-op blocks, the counter circuit and write amplifier will operate as explained, but when the iiip-fiop reverses the CPlB pulses will be blocked from the counter and amplifier.

Pulse CP1.S is fed into an inverter amplifier 214, the output being equivalent to C1105. This pulse then enters the set 1 of flip-iiop 212. Set 0 of the same flip-flop comes from the output of the fourteenth stage of the magnetic distributor that is a portion of the lov speed clock 200. If pulses appear on the set fi and set `li inputs at the same time set will override set 1. A pulse `will then appear at set 1 every two microseconds (CPG), and at the end of the fourteenth output distributor a pulse will also appear on the set 0 input. Set then will take over and inhibit the next CP1B pulse. Two microseconds later ip-fiop will be set 1 and the inhibit will be removed from CP1B. This means it will take seventeen inputs to completely cycle the associated sixteen stage distributor. The CPGS pulse also goes to an emitter follower amplifier to supply `the read pulse for load cores.

The magnetic distributor shown in FIG. 2A receives its input pulses from the aforementioned driver circuitry with pulses alternately appearing on leads CCG-1 and CCG-2. These pulses will be steered to one of the sixteen load cores and set the core to a l state. All load cores are connected in series to the read pulse which cornes every two microseconds in the 1/2 microsecond prior to thc write pulse. The outputs of the load cores designated 221 to 22S, and 251 to 258 are connected to OR gate circuits and into four ip-iiops shown in FIG. 2B designated 261, 262, 263 and 264. The operation of the distributor is similar to that of the high-speed distributor as previously described.

The four hip-flops 261, 262, 263 and 264 receive set pulses from .the distributor, and based on their respective output conditions supply pulses to OR gate circuits 265, 269 and 271 to 278. The output at each of these gates is supplied to a pulse amplifier 281 to 239 and 291 to 294 as shown on FIG. 2B. The outputs from each of these amplifiers are gated in most instances by CP1.5 pulses from the high-speed clock. The outputs of the amplifiers are the pulses designated as P1, P2, P3, P4, P5, P6, P7, P, P9, P10, P11, P12, P13, P14 and P115. These pulses are used as previously described throughout the entire system.

The low-speed magnetic distributor 300 is shown in FIG. 3. Low-speed clock pulses B1 and B12 enter the driver circuitry consisting of fiip-flops 311 and 312 and amplifiers 331 to 338, inclusive. The flip-hops compiise a scale of four counter and are triggered by a P pulse from the low-speed clock 200. The outputs of these flipfiops are gated with P1 and P12 pulses by gates 321 to 328, inclusive, to provide one of the amplifiers in each of the four amplifier groups to operate for each pulse. Pulses P1 and P12 each appear on one of the four output leads and each pair of pulses will be used to drive one of the ten stage magnetic distributors 340, 370, 380 or 390. Each of these distributors will receive every fourth P1 and P12pulse and therefore there will be a total distribution of forty stages.

The necessary condition for the performance of logic operation is such in the case of the links, the calling party time slot must be in the same time slot as ya. P2' pulse of the logic cycle and that the called time slot must be in conjunction with P3. In the case of trunks, the trunk time slot must coincide with P2. The P2 of the logic cycle for any particular distributor output will always be coincident with the same DP pulse in the high-speed memory; also each of the forty logic cycles in the dis- 1.2 tributor will be coincident with a different DP pulse than any of the other thirty-nine logic cycles.

The lowspeed memoryf() is shown in FIG. 4. Its configuration is similar to that for the high-speed memory previously discussed with the first twenty-eight rows being used for the link rows, the odd-numbers for the calling party, the even for the called. Since a P2 pulse is coincident with the calling party and not the called, then the logic cycle with P2 coincident with the called time slot should not appear lin the memory. All logic cycles that have P2 coincident with the even-number DP pulse from l to 28 would not appear as rows in the low-speed memory. Each row in the memory will be read every 1360 microseconds setting ip-fiops in the register control 150. Logical operations will then be performed. Twenty microseconds later the information will be written back into the memory for storage until the next read 1360 microseconds later.

In an electronic PABX telephone system as disclosed in this application the low-speed clock 200, low-speed distributor 300 and low-speed memory 400 and high-speed distributor 500 and memory 600 must start in proper phase with one another. The read pulse for row 1 of the high-speed memory must start at the same time as pulse P1 of the low-speed clock 200 and the read pulse for row l of the low-speed memory 406. Because of this requirement a system phaser 900 is used to set the proper cores in the high and low-speed distributors and the lowspeed clock and also to set the hip-flops in the high and low-speed driver circuitry so that the memories 400 and 600 will be in phase.

Referring now to FIG. 9 the system phaser includes three transformers 901, '902 and 903. A preset winding passes through each of these transformers and upon application of a positive voltage by means of a push button to this preset winding it will cause flip-flop 920 to reverse its state to turn on amplifiers 930 and 940. Turning on these amplifiers prevents read pulses from entering the high-speed or low-speed driver circuitry. The instant the preset button 999 is released the distributor circuitry in the low-speed clock 200 will start operating. Ihe state of flip-flops 211 and 212 is not important since the circuit arrangement in the low-speed clock is such that no matter what state they are in the clock will be running properly before the appearance of a P13 pulse. A CP05 pulse will have occurred at least once by the time the P13 appears and therefore ip-ops in registers 136 and 190 will be set 0 and the appearance of the P13 will set all the low-speed register dip-flops to state 0. The P13 pulse entering the system phaser 900 will be amplified by amplifier 910 and will cause a read-out pulse to appear from the primary windings of transformers 901, 962 and 903. The output of transformer 901 sets the counter 511 in the high-speed core driver circuitry to the proper starting state while T2 and T3 set the counter flipflops in the low-speed core driver circuitry to the proper starting condition. P13 also applies a pulse to flip-flop 92E) reversing its state and turning amplifiers 930 and 940 off. The inhibit placed by these amplifiers on the CPO.S and the P1 pulses respectively are removed so both pulses commence at the end of a P13 pulse. At this time all conditions are met so the low and high-speed memories 406i and 600 will start in proper phase with the low-speed clock 200.

What is claimed is:

l. In a time division multiplex Comunication system, a plurality of stations including` a calling station and a called station, a transmission highway, switching means operable to establish a connection between said calling station and said called station over said transmission highway, register means responsive to the initiation of a call by said calling station to control said switching means, and a memory system effective to operate said register means and said switching means comprising: a pulse source; first storage means including a plurality of ferrite spa-asas -1,3 cores arranged in matrix form, each of said cores having circuitconnections to saidregistering means; second storage means including a plurality of ferrite cores arranged in matrixform, each of said c ores including circuit connections to said register means and to `said switching lmeans; rst pu'lse distributing means comprising auplurality .of pulse distributor circuits each including a plu ralityoi output circuit connections connected to saidfirst storagemeans, and a ,plurality ofjinput connections; pulse dividing means comprising a plurality of amplifiers each having an outputrterrnination connected to said'first pulse distributing means, a plurality of gate circuits each connectedat ,therinputvof one off said amplifiers and each of said gate circuits having connections to a scale o'f 'four counter, a multi-stage current steering type pulse distributor having a plurality .of circuit connections to said pulsesource, and having circuit connections to said vscale of four counter; second pulse distributingmeans comprising a plurality `of pulse distributor circuits each including a plurality -of output circuits connected Lto said second Storage means a .plurality of' rinput terminals connected to said. pulse source; .wherebysaid memory system is elective to v establish a V.connection over said transmission highway .between saidcallingstation and said called station.

2. :In ,a time division multiplex communication system, va plurality of stations including, a c allingstation and `a called station, A:a .transmission highway, .switching means operable ,to .establish a connection between said Acalling station and saidicalled stationover saidtransmissionhighway, register means responsivetothe initiation of;a rcall .by said calling station .tocontrol said switchingzmeans, and a memory system `eiective to operate said register ,means and said :switching means comprising a ,pulse source; first storage means including a plurality of ferrite cores arranged .in ,matrix form, :each ,of said cores having circuit connections to said registeringmeanm second storage means including `a .pluralityof ferrite coresarranged in .matrix form, .eachof Saidcores includingcircuit connections ,to said Aregister means and .to said switching means; iirst pulse distributing means vcomprising a vplurality :of pulse distributor circuits each .including va plurality ofzoutput circuitconnections connected to said first storage means, and afpluralityofinput counections;;pulse dividing means comprising a pluralityof amplifierseach having an ,Output.terminationrconnected to said first pulse distributing means, a Iplurality oiugate :circuits eacliconnested at kthe input otone of said amplifiers and each of ysaid. gate :circuits having connections to 'a scale ot Yfour counter, :a multi-stage current steering' type pulse distributor yhaving a plurality of circuit connections to said lpulse source, andvhaving circuit connectionsto said scale of four counter; second pulsedistributingmeans comp-rising a pluralityof pulse .distributorcircuits each including ta plurality of `output circuits connected -to vsaid second storage means a plurality of input terminals yconnected to said pulse source; and phasing-means-including a plurality of transformers each having a control winding extending to either of said pulse distributing means; whereby said first and second pulse distributing means are rendered effective to transmit pulses to .said;rst and ,second storage means in proper phase relationship and said memory system is effective to establish a=connection over said transmission highway ybetween said calling station and said called station.

3. in a time division multiplex communication system, a plurality of stations including, a calling station and a called station, a transmission highway, switching means operable to establish a connection between said calling station and said called station over said transmission highway, register means responsive to the initiation of a call by said calling station to control said switching means, and a memory system effective to operate said register means and said switching means comprising: a pulse source; first storage means including a plurality of lferrite cores arranged in matrix form, each of said cores having circuit ,-14 connections to said register means; secondstorage means including a ,plurality otfferrite Acores arranged in matrix Iform, each of said cores including circuit connections to said register means and said switching meansyfirstpulse distributing means connected to said rst storage means; pulse dividing means 'including circuit connections to said pulse source and to said rst pulse distributing means; second pulse distributing means connectedto said second storage vmeans and also `including circuit connections to said pulse source; whereby said memory system is effective to establish a connection o ver said transmission 'highway between said calling station and said called station.

f4. In a communication system the combination `as .claimedn claim 3, lwherein said'irst storage means include a plurality of ferrite cores :arranged in matrix form comprising a plurality of horizontal rows and a yplurality of vertical rows, each of said vertical rows including a sense winding in commonwith lall of said cores insaidrow and a partiialled Write winding common to all of said cores 'in said row, each .of said horizontal rows ,including appar-tial write winding common .to all of said cores 1in said row and a read winding common to all of said cores in said row, -all of said sense-windings and said partial write windings in said vertical rows havingcircut connections to said register means; each ofsaidlpartial write windings and said read windingsin allof saidihorizontal rows having circuit connections to said npulse distribution means.

5. VIn Aa communication system the combination as claimed in .claim 3V, .whereinsaid second storage -means 'include a plurality of ferrite cores arranged in matrix form comprising a plurality of :horizontal rows. and aplurality of vertical rows, each ofsa'id vertical rows including a sense `winding vin common withall of said c ores in `said row and apartialled .write winding common to a'll of said cores 'in said rowfeach of said horizontal rows including a partial Ywrite winding common to all of said cores in said row and a read winding common to all of said cores in said row, all of said sense windings and said partial write windings in said vertical rows having circuit connections to .said ,register means; each of said partial write windings 4and said read windings in Iall of sa'id `horizontal rowshaving circuit connections yto saidpulse distribution means; and Aeach of said partial write wind-rY ings in all of said horizontal rows having circuit connections to said switching means.

v6. In la communication system the 4combination uas claimed in claim 3, whereinsaid lirst pulse distribution means comprise: a counter including a bistable multiyibratorgapluralityof gate circuits having circuit Aconnections to said pulse source/and 'to said'multivibrator; a plurality of amplifier circuits eachhaving circuit connections to a different one of said plurality of gate circuits; and' a plurality of current steering distributor fcircuits each adapted to receive pulses from rand having circuit connections tor'two of said amplifiers; -said current steering distributor circuits each including va plurality A of connections-to saidfirst storagemeans. i

7. In a communication Ysystem 'the combination as claimed in claim 3, wherein Ysaid-pulse dividing-means comprising a scale of two counter Lhaving input circuit connections Ato said Y,pulse source; a plurality l`of nmultivibrators; la pulse distribution matrix connecting said Vscale of two counter-to saidplurality of-multiuibnatorsg-a-plural ity of output amplifiers; and a plurality of gate circuits each having a plurality of input connections connected to said multivibrators and an output connection connected to said amplifiers; the output terminals of said amplifiers including a plurality of circuit connections to said rst pulse4 distribution means.

8. In -a communication system the combination as claimed in claim 3, wherein said second pulse distribution means comprise: a counter including a Erst bistable multivibrator; a second bistable multivibrator having circuit connections to said first multivibrator; a plurality of gate circuits having circuit connections to said pulse source and to said first and second multivibrators; a plurality of ampliiier circuits each having circuit connections to a different one of said plurality of gate circuits; and a plurality of current steering distributor circuits each `adapted to receive pulses from and having circuit connections to two of said amplifiers; said current steering distributor circuits each including a plurality of connections to said second storage means.

9. In a time division multiplex communication system, a plurality of stations including, a calling station and a called station, a transmission highway, switching means operable to establish a connection between said calling station and said called station over said transmission highway, register means responsive to the initiation of a call by said calling station to control said switching means, and a memory system eiective to operate said register means and said switching means comprising: a pulse source; first storage means including a plurality of ferrite cores arranged in matrix form, each of said cores having circuit connections to said register means; second storage means including a plurality of ferrite cores arranged in matrix form, each of said cores having circuit connections to said register means and to said switching means; iirst pulse distributing means connected to said first storage means; pulse dividing means including circuit connections `to said pulse source and to said iirst pulse distributing means; second pulse distributing means connected to said second storage means and also including circuit connections to said pulse source; and phasing means having separate circuit connections to each of said iirst and second pulse distributing means; whereby said iirst and second pulse distributing means are rendered effective to transmit pulses to said first and second storage means in proper phase relationship and said memory system is elective to establish a connection over said transmission highway between said calling station and said called station.

l0. `In a communication system the combination as claimed in claim 9, wherein said first storage means include a plurality of ferrite cores arranged in matrix form comprising a plurality of horizontal rows and a plurality of vertical rows, each `of said vertical rows including a sense winding in common with all of said cores in said row and a partial write winding common to all of said cores in said row, each of said horizontal rows including a partial write winding common to all of said cores in said row and a read winding common to all of said cores in said row, all of said sense windings and said partial write windings in said vertical rows having circuit connections to said register means; each of said partial write windings and said read windings in all of said horizontal rows having circuit connections to said pulse distribution means.

11. In a communication system the combination as claimed in claim 9, wherein said second storage means include a plurality of `ferrite cores arranged in matrix form comprising a plurality of horizontal rows and a plurality of vertical rows, each of said vertical rows including a sense winding in common with all of said cores in said row and a partialled write winding common to all of said cores in said row, each 'of said horizontal rows including a partial write winding common to all of said cores in said row and a read winding common to all of said cores in said row, all of said sense windings and said partial Write windings in said vertical rows having circuit connections to said register means; each of said partial write windings and said read windings in all of said horizontal rows having circuit connections to said pulse distribution means; and each of said partial write windings in all of said horizontal rows having circuit connections to said switching means.

l2. In a communication system the combination as claimed in claim 9, wherein said first pulse distribution means comprise: a counter including a bistable multivibrator; a plurality of gate circuits having circuit connections to said pulse source and to said multivibrator; a plurality of amplifier circuits each having circuit connections to a different one of said plurality of gate circuits; and a plurality of current steering distributor circuits each adapted to receive pulses from and having circuit connections to two of said amplifiers; said current steering distributor circuits each including a plurality of connections to said first storage means.

`13. In a communication system the combination as claimed in claim 9, wherein said pulse dividing means comprising a scale of two counter having input circuit connections to said pulse source; a plurality of multivibrators; a pulse distribution matrix connecting said scale of two counter to said plurality of multivibrators; a plurality of output amplifiers; and a plurality of gate circuits each having a plurality of input connections connected to said multivibrators and an output connection connected to said amplifiers; the output terminals of said ampliers including a plurality of circuit connections to said first pulse distribution means.

14. In a communication system the combination as claimed in claim 9, wherein said second pulse distribution means comprise: a counter including a tirst bistable multivibrator; a second bistable multivibrator having circuit connections to said iirst multivibrator; a plurality of gate circuits having circuit connections to said pulse source and to said rst and second multivibrators; a plurality of amplifier circuits each having circuit connections to a different one of said plurality of gate circuits; and a plurality of current steering distributor circuits each adapted to receive pulses from and having circuit connections to two of said amplifiers; said current steering distributor circuits each including a plurality of connections to said second storage means.

15. In a communication system the combination as claimed in claim 9, wherein said phasing means includes: a plurality of transformers, each of said transformers having an individual circuit connection to one of said pulse distributors; a switch connected to a source of direct current and adapted to extend direct current to said transormers; a multivibrator having input connections to said switch and to said pulse dividing means; a plurality of inverter amplifiers having their outputs connected to said pulse distributors and each having a irst input connected to said multivibrator and a second input connected to said pulse dividing means.

References Cited in the tile of this patent UNITED STATES PATENTS 2,754,367 Levy July 10, 1956 2,766,327 Lesti Oct. 9, 1956 2,854,516 Faulkner Sept. 30, 1958 

